Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751331AbaLPFdf (ORCPT ); Tue, 16 Dec 2014 00:33:35 -0500 Received: from mail-oi0-f45.google.com ([209.85.218.45]:54344 "EHLO mail-oi0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750856AbaLPFdd (ORCPT ); Tue, 16 Dec 2014 00:33:33 -0500 MIME-Version: 1.0 In-Reply-To: <20141216005048.GA3802@dtor-ws> References: <20141216005048.GA3802@dtor-ws> Date: Tue, 16 Dec 2014 11:03:33 +0530 Message-ID: Subject: Re: [PATCH] cpufreq: imx6: prorect calls to dev_pm_opp_get_opp_count with RCU lock From: Viresh Kumar To: Dmitry Torokhov Cc: "Rafael J. Wysocki" , Shawn Guo , Philipp Zabel , Anson Huang , John Tobias , "linux-pm@vger.kernel.org" , Linux Kernel Mailing List Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 16 December 2014 at 06:20, Dmitry Torokhov wrote: > dev_pm_opp_get_opp_count() must be called with RCU lock held. > > Signed-off-by: Dmitry Torokhov > --- > > Not tested at all... > > drivers/cpufreq/imx6q-cpufreq.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/cpufreq/imx6q-cpufreq.c b/drivers/cpufreq/imx6q-cpufreq.c > index 380a90d..851d4fd 100644 > --- a/drivers/cpufreq/imx6q-cpufreq.c > +++ b/drivers/cpufreq/imx6q-cpufreq.c > @@ -200,7 +200,9 @@ static int imx6q_cpufreq_probe(struct platform_device *pdev) > * Just, incase the platform did not supply the OPP > * table, it will try to get it. > */ > + rcu_read_lock(); > num = dev_pm_opp_get_opp_count(cpu_dev); > + rcu_read_unlock(); > if (num < 0) { > ret = of_init_opp_table(cpu_dev); > if (ret < 0) { > @@ -211,7 +213,9 @@ static int imx6q_cpufreq_probe(struct platform_device *pdev) > /* Because we have added the OPPs here, we must free them */ > free_opp = true; > > + rcu_read_lock(); > num = dev_pm_opp_get_opp_count(cpu_dev); > + rcu_read_unlock(); > if (num < 0) { > ret = num; > dev_err(cpu_dev, "no OPP table is found: %d\n", ret); This one looks fine for sure but I was wondering for the users which just need to call opp-count from under the locks, what about something like: dev_pm_opp_get_opp_count_locked() ? -- viresh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/